In rolls of the kind generally mentioned above—which by those skilled in the art are referred to as combi rolls—it is important that the roll rings are kept pressed in close contact against occurring spacer rings in order for the rings not to slip in relation to each other. For this purpose, solely the lock nut itself is inadequate, and therefore it is necessary to arrange, in the set of rings, at least one powerful spring, which for a long time continuously can apply a spring prestress to the rings. For this purpose, Belleville springs, among others, have previously been used (see, for instance, U.S. Pat. No. 5,735,788). However, for many different reasons, the use of Belleville springs has not been successful. One of these reasons is that such springs have a tendency to slacken or be fatigued too fast. Another reason is that a Belleville spring only has line contact with adjacent rings and not surface contact.